The whole earth resonance concept still involves both electric and magnetic fields.. or in general E-M fields.
As I understand it, Tesla's idea was to maintain a "reservoir" of energy in the resonant spherical tank circuit. I doubt that he anticipated the energy densities that would be required to power our society. Global power consumption is at Petawatt (1E15)levels now, with the majority of the world still in a proto-industrialized state.
A plethora of practical problems exist in extracting this power from the distributed e-m field. First are the actual power densities at ground level. The earth has some 200 million square miles of surface including the oceans. At about 1.3E11 cu ft/cu mile, that makes about 2.6E19 cubic ft per mile of spherical shell atmosphere. Thus 1E15 watt power levels create about 0.1mW per cubit ft per mile of excited atmosphere height, and proportionately lower for greater heights. Pick any number you want for the effective height of the resonant capacitor and you can see there is a power level of micro-watts /cu ft.
To pickup a few kw power would take more property than most people own, just to house the antenna.
Further, there are many conducting structures, man-made and natural, so that losses could be prohibitive.
Directed wireless energy delivery seems more practical, but means are needed to keep the public out of the beams for safety reasons. I think there is promise for this mode of energy delivery, but none of the requisite infra-structure presently exists.
Dave Cooper
Created on Monday, May 07, 2001 1:33 AM EDT by David Cooper